24.3.2.4.3 Parity Checker

When enabled, the parity checker calculates the parity of the data bits in incoming frames and compares the result with the parity bit of the corresponding frame. If a parity error is detected, the Parity Error flag (PERR in USART.RXDATAH) is set.

If USART LIN mode is enabled (by writing RXMODE to '1' in USART.CTRLB), a parity check is only performed on the protected identifier field. An parity error is detected if one of the equations below is not true which sets PERR in USART.RXDATAH.

P0=ID0⊕ID1⊕ID2⊕ID4P1=¬(ID1⊕ID3⊕ID4⊕ID5) 
Figure 24-6. Protected identifier field and mapping of identifier and parity bits